Anatomy of the diaphragm

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Anatomy of the diaphragm

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Anatomy of the Diaphragm

Figure 1: A. Anterior view of the diaphragm with nerves. B. Inferior view of the diaphragm and diaphragmatic openings. 
Figure 2:  Arteries of the diaphragm.
Figure 3: Veins of the diaphragm.
Figure 4: Lymphatic drainage of the diaphragm.
  • Sternal part: posterior aspect of the xiphoid process
  • Costal part: internal surfaces of the 7th to the 12th ribs 
  • Lumbar part:  medial and lateral arcuate ligaments 
  • Central Tendon
  • Motor: 
    right and left phrenic nerves (C3-C5)
  • Sensory:

  • Central: Phrenic nerves

    Peripheral: T5-T11 intercostal nerves and subcostal nerves
  • Chief muscle for inspiration
Major apertures
Caval opening
  • Central tendon of the diaphragm slightly to the right of the median plane
  • T8 vertebra
  • Inferior vena cava 
  • Terminal branches of the right phrenic nerve
Esophageal hiatus
  • Right crus of the diaphragm at the level of the T10 vertebra
  • Esophagus
  • Esophageal branches of the left gastric vessels
  • Anterior and posterior vagal trunks
Aortic hiatus
  • Posterior to the diaphragm at the level of the T12 vertebra
  • Descending aorta
  • Azygos vein
  • Hemiazygos vein
  • Thoracic duct


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The left musculophrenic artery is indicated in the image below.

Memory Anchors and Partner Content


The diaphragm is a dome-shaped sheet of skeletal muscle that divides the thoracic cavity from the abdominal cavity.

That may sound simple, but in fact, the diaphragm is so much more than just a sheet of muscle. In fact, every breath you take is thanks to your diaphragm!

Ok, so let’s begin by looking at the general structure of the diaphragm. It curves superiorly into right and left domes.

It has a mobile, central portion known as the central tendon and a peripheral muscular portion that is fixed to the bones, cartilages, and ligaments of the thoracic cage.

The periphery of the diaphragm can be divided into three parts depending on its specific attachment points.

The sternal part, attaches to the posterior aspect of the xiphoid process; the costal part attaches to the internal surfaces of the 7th to the 12th ribs and their costal cartilages; while the lumbar part attaches to the medial and lateral arcuate ligaments, the L1 to L3 vertebral bodies and the intervertebral discs in between.

Now, the diaphragm is the chief muscle for inspiration; meaning that when it contracts, it helps us breathe in. During contraction, the central portion of the diaphragm depresses, increasing the volume of the thoracic cavity, which, in turn, increases the volume in the lungs.

This makes the intrapulmonary pressure fall below the atmospheric pressure, creating a partial vacuum that allows fresh air to be sucked in!

On the other hand, expiration is largely passive, meaning the diaphragm relaxes and rises, which decreases the volume of the thoracic cavity, and subsequently increases the intrapulmonary pressure to be above the atmospheric pressure, forcing the air in the lungs to be expelled out.


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  2. "Encyclopaedia Britannica Print Set " Encyclopedia Britannica Inc; 15th edition (2009)
  3. "Median Arcuate Ligament Syndrome: Evaluation with CT Angiography" RadioGraphics (2005)
  4. "Median arcuate ligament syndrome" Current Treatment Options in Cardiovascular Medicine (2008)
  5. "Gray's Anatomy" Churchill Livingstone (2015)
  6. "Wheater's Functional Histology" Churchill Livingstone (2013)
  7. "Essential Clinical Anatomy" Lippincott Williams & Wilkins Essential Clinical Anatomy (2010)
  8. "Our current understanding of the lymphatics of the brain and spinal cord" Clinical Anatomy (2018)

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